Allometric models to estimate tree height in northern Amazonian ecotone forests

Abstract

Allometric models defining the relationship between stem diameter and total tree height in the Amazon basin are important because they refine the estimates of tree carbon stocks and flow in the region. This study tests different allometric models to estimate the total tree height from the stem diameter in an ecotone zone between ombrophilous and seasonal forests in the Brazilian state of Roraima, in northern Amazonia. Stem diameter and total height were measured directly in 65 recently fallen trees (live or dead).Linear and nonlinear regressions were tested to represent the D:H relation in this specific ecotone zone. Criteria for model selection were the standard error of the estimate (S yx ) and the adjusted coefficient of determination (R² adj ), complemented by the Akaike Information Criterion (AIC). Analysis of residuals of the most parsimonious nonlinear models showed a tendency to overestimate the total tree height for trees in the 20-40 cm diameter range. Application of our best fitted model (Michaelis-Menten) indicated that previously published general equations for the tropics that use diameter as the independent variable can either overestimate tree height in the study area by 10-29% (Weibull models) or underestimate it by 8% (climate-based models). We concluded that our site-specific model can be used in the ecotone forests studied in Roraima because it realistically reflects the local biometric relationships between stem diameter and total tree height. Studies need to be expanded in peripheral areas of northern Amazonia in order to reduce uncertainties in biomass and carbon estimates that use the tree height as a variable in general models. Modelos alométricos para estimar altura de árvores em florestas ecotonais do norte da Amazônia RESUMOModelos alométricos que definem o relacionamento entre diâmetro do tronco e a altura total da árvore na bacia amazônica são importantes porque refinam as estimativas de fluxo e estoques de carbono arbóreo na região. Este estudo testou diferentes modelos alométricos para estimar a altura total de árvores a partir do diâmetro do tronco em uma zona de ecótono entre florestas ombrófilas e sazonais no estado de Roraima, norte da Amazônia. Diâmetro do tronco e altura total foram medidos de forma direta em 65 árvores tombadas recentemente (vivas e mortas). Regressões linear e não-linear foram testadas para representar a relação D:H nesta zona específica de ecótono. Os critérios de seleção dos modelos foram o erro padrão da estimativa (S yx ), o coeficiente de determinação ajustado (R² adj ) e o Critério de Informação de Akaike (AIC). A análise dos resíduos dos modelos não-lineares mais parcimoniosos mostrou uma tendência de superestimar a altura total para árvores entre 20-40 cm de diâmetro do tronco. A aplicação do modelo melhor ajustado (Michaelis-Menten) indicou que equações gerais publicadas previamente para os trópicos que usam diâmetro como variável independente podem superestimar em 10-29% (modelos Weibull) ou subestimar em 8% (modelos baseados no clima) a altura da...

Floristic composition in ecotone forests in northern Brazilian Amazonia: preliminary data

“…The floristic survey included measurements of stem diameter (diameter tape - precision 0.1 cm), collecting botanical material and general description of the individuals/species, following standardised tree measurement methods established for PPBio grids and modules (Castilho et al 2004). Palm height was estimated with Android technology using the Measure Height App (Oü 2014), while trees height was estimated by regression using a Maracá-specific allometric model (Barbosa et al 2019).…”

Pedoenvironments driving the monodominance of Peltogyne gracilipes (Leguminosae) in the Northern Amazon, Brazil

“…All the samples were homogenized, air dried and sieved (2 mm) for chemical analysis and granulometry (EMBRAPA, 2011). The soil analysis data is freely available in the study by Barbosa et al, (2019).…”

“…Todas as amostras foram homogeneizadas, secas ao ar e peneiradas (2 mm) para análise química e determinação da granulometria (EMBRAPA, 2011). O conjunto de dados relativo as análises de solo pode ser livremente acessado em Barbosa et al (2019).…”

An accuracy analysis of mangrove tree height mensuration using forestry techniques, hypsometers and UAVs

“…Previous studies have shown that tree heights improve biomass estimates as compared with diameter only in allometric relations for tropical forest trees (Chave et al, 2005;Hunter et al, 2013;Phalla et al, 2017;Ekoungoulou et al, 2018;Xu et al, 2019). Quite a number of studies on biomass estimation with tree heights used only one method to measure tree height with most studies using the clinometer for tree height mensuration (Hunter et al, 2013;Sullivan et al, 2018;Bhatta et al, 2018;Dube et al, 2018;Kim et al, 2018;Muhati et al, 2018;Fajardo, 2018;Latifah et al, 2018;Owino et al, 2018;Barbosa et al, 2019). Few studies used different forms of hypsometers varying from Haglof Vertex III to Nikon Forestry Pro (Kearsley et al, 2013;Wu et al, 2016;Sullivan et al, 2018;Ekoungoulou et al, 2018) and to different models of Blume Leiss altimeters (Lim and Cousens, 1986;Williams et al, 2003;Kitikidou et al, 2014;Hirankhede et al, 2017;Padmakumar et al, 2018).…”